#define  _CRT_SECURE_NO_WARNINGS
class Solution
{
public:
    int minNumberOfFrogs(string croakOfFrogs)
    {
        string t = "croak";
        int n = t.size();
        vector<int> hash(n);
        unordered_map<char, int> index; 
    for (int i = 0; i < n; i++)
         index[t[i]] = i;

    for (auto ch : croakOfFrogs)
    {
        if (ch == 'c')
        {
            if (hash[n - 1] != 0) hash[n - 1]--;
            hash[0]++;
        }
        else
        {
            int i = index[ch];
            if (hash[i - 1] == 0) return -1;
            hash[i - 1]--; hash[i]++;
        }
    }
    for (int i = 0; i < n - 1; i++)
        if (hash[i] != 0)
            return -1;
    return hash[n - 1];
    }
};